二叉树中序遍历-非递归版

算法思想:每次把最左边的加到栈里,一直到没有左结点,从栈中取数据并打印,把右孩子当作头再遍历该子树

  package com.algorithm.practice.tree.traversal;

import java.util.Stack;

public class InOrderPrint {
    public static class Node {
        public int value;
        public Node left;
        public Node right;

        public Node(int data) {
            this.value = data;
        }
    }

    public static void  InOrderPrint(Node head){
        System.out.print("in-order: ");
        if (head!=null){
            Stack stack=new Stack<>();
            while (!stack.isEmpty()||head!=null){
                if (head!=null){
                    stack.push(head);
                    head=head.left;
                }else {
                    head=stack.pop();
                    System.out.print(head.value+" ");
                    head=head.right;
                }
            }

        }
    }
    public static void main(String[] args){
        Node head = new Node(5);
        head.left = new Node(3);
        head.right = new Node(8);
        head.left.left = new Node(2);
        head.left.right = new Node(4);
        head.left.left.left = new Node(1);
        head.right.left = new Node(7);
        head.right.left.left = new Node(6);
        head.right.right = new Node(10);
        head.right.right.left = new Node(9);
        head.right.right.right = new Node(11);
        InOrderPrint(head);
        System.out.println();
    }
}